Fingerprint sensor and button combinations and methods of making same

ABSTRACT

A biometric sensor may comprise a plurality of a first type of signal traces formed on a first surface of a first layer of a multi-layer laminate package; at least one trace of a second type, formed on a second surface of the first layer or on a first surface of a second layer of the multi-layer laminate package; and connection vias in at least the first layer electrically connecting the signal traces of the first type or the signal traces of the second type to respective circuitry of the respective first or second type contained in an integrated circuit physically and electrically connected to one of the first layer, the second layer or a third layer of the multi-layer laminate package.

CROSS-REFERENCE

This application is a continuation of copending U.S. patent applicationSer. No. 16/399,074, filed on Apr. 30, 2019, which is a continuation ofU.S. patent application Ser. No. 15/489,561, filed on Apr. 17, 2017, nowU.S. Pat. No. 10,325,132, which is a continuation of U.S. patentapplication Ser. No. 14/050,012, filed on Oct. 9, 2013, now U.S. Pat.No. 9,651,513, which claims priority to U.S. Provisional PatentApplication No. 61/713,550, filed on Oct. 14, 2012, and U.S. ProvisionalPatent Application No. 61/754,287, filed on Jan. 18, 2013. All of theforegoing applications are incorporated by reference in theirentireties.

BACKGROUND OF THE INVENTION

Biometric sensors and imagers, including, e.g., fingerprint sensors andimagers like those disclosed in the present application are known in theart and are disclosed, e.g., in U.S. Pat. Nos. 7,099,496 to Benkley,issued Aug. 29, 2006, for SWIPED APERTURE CAPACITIVE FINGERPRINT SENSINGSYSTEMS AND METHODS; U.S. Pat. No. 7,463,756 to Benkley, issued Dec. 9,2009, for FINGER POSITION SENSING METHODS AND APPARATUS; U.S. Pat. No.8,165,355 to Benkley, issued Apr. 24, 2012, for METHOD AND APPARATUS FORFINGERPRINT MOTION TRACKING USING AN IN-LINE ARRAY FOR USE IN NAVIGATIONAPPLICATIONS; U.S. Pat. No. 7,751,601 to Benkley, issued Jul. 6, 2010,for FINGER SENSING ASSEMBLIES AND METHODS OF MAKING; and US PatentApplication Publication Nos. US2011/0304001, published Dec. 15, 2011,entitled FINGERPRINT SENSING CIRCUIT; US2012/0189166 published Jul. 26,2012, entitled USER INPUT UTILIZING DUAL LINE SCANNER APPARATUS ANDMETHOD; and US2012/0256280, published Oct. 11, 2012, entitled PACKAGINGFOR FINGERPRINT SENSOR AND METHOD OF MANUFACTURE. As these types ofsensors are used in more and more forms of portable/mobilecomputing/communications devices, such as cell phones, Blackberries, andother forms of personal digital assistants (“PDAS”), electronic pads,tablets, notebooks, etc. (collectively “portable computing devices”),there is a need for both a more miniaturized, especially thinner, anddurable sensor device.

Such sensors have also been incorporated into and/or integrated withsuch user portable/mobile computing/communications devices and, inparticular can be integrated with a button on such a user device thatperforms some other function for the user device other than gatheringbiometric data for user authentication or other uses. It has becomeimportant, therefore, for such sensors, when so incorporated/integrated,to be durable and able to survive somewhat extreme conditions of stress,as an example, during failure testing, such as drop testing, and thenlater while in actual use. The present application addresses variousaspects of this need in the art.

Since its inception, fingerprint sensing technology has revolutionizedbiometric identification and authentication processes. In most cases, asingle fingerprint can be used to uniquely identify an individual in amanner that cannot be easily replicated or imitated. The ability tocapture and store fingerprint image data in a digital file of minimalsize has yielded immense benefits in fields such as law enforcement,forensics, and information security.

However, the widespread adoption of fingerprint sensing technology in abroad range of applications has faced a number of obstacles. Among theseobstacles is the need for a separate and distinct apparatus forcapturing a fingerprint image. Additionally, such components are oftenimpractical for use in systems that are designed to be of minimal sizeor weight. As handheld devices begin to take on a greater range offunctionality and more widespread use, engineers and designers of suchdevices are constantly seeking ways to maximize sophistication and easeof use while minimizing size and cost. Typically, such devices onlyincorporate input/output components that are deemed to be essential tocore functionality, e.g., a screen, and a limited set of buttons.

For these reasons, fingerprint-based authentication techniques have notreplaced username and password authentication in the most commoninformation security applications such as email, online banking, andsocial networking. Paradoxically, the growing amount of sensitiveinformation Internet users are entrusting to remote computer systems hasintensified the need for authentication procedures more reliable thanpassword-based techniques.

An electronic device having a button interface with built-in fingerprintsensing capability would thus lead to increased adoption offingerprint-based authentication. As will be seen, the presentdisclosure provides such a system that overcomes obstacles associatedwith incorporating a fingerprint sensor into an electronic device buttoninterface.

SUMMARY

It will be understood by those skilled in the art that there isdisclosed in the present application a biometric sensor that maycomprise a plurality of a first type of signal traces formed on a firstsurface of a first layer of a multi-layer laminate package; at least onetrace of a second type, formed on a second surface of the first layer oron a first surface of a second layer of the multi-layer laminatepackage; and connection vias in at least the first layer electricallyconnecting the signal traces of the first type or the signal traces ofthe second type to respective circuitry of the respective first orsecond type contained in an integrated circuit physically andelectrically connected to one of the first layer, the second layer or athird layer of the multi-layer laminate package. The first type ofsignal trace may comprise drive signal traces and the second type oftraces may comprise at least one receive signal trace or the first typeof traces may receive signal traces and the second type of tracescomprising at least one drive signal trace. The at least one trace ofthe second type may comprise one trace of the second type and the sensormay comprise a one dimensional linear array capacitive gap biometricsensor. The at least one trace of the second type may comprise aplurality of traces of the second type and the sensor may comprise a twodimensional grid array capacitive gap biometric sensor.

The first layer may comprise a circuit board layer and the second layermay comprise a core layer attached to one side of the circuit boardlayer. A third layer comprising a circuit board layer may be attached toanother side of the core layer. The biometric sensor may be encapsulatedon all sides except for a top finger sensing side and may be attached toa substrate. The biometric sensor may be encapsulated on all sides. Thebiometric sensor may be encapsulated by moldable plastic material formedaround the package by a molding process, which also may form anencapsulation molded with rounded edges and corners. The biometricsensor may comprise a biometric sensor mounted on a portable electronicdevice, and may also cooperate mechanically with elements of a switch,e.g., within the housing of the portable computing device, to operatethe switch, i.e., act as a switch operating button.

A user interface, e.g., a button, suitable for incorporation into anelectronic device, such as a laptop, tablet, or smart phone or otherportable computing devices is disclosed, as well as methods of use andmethods of manufacture. The interface can have a housing with a smallprofile with a thickness less than or equal to 3 mm, an upper layerwhich fits within a user device housing and sits atop one or more setsof sensor traces in communication with a chip external to the interfacevia a flexible circuit.

An aspect of the disclosure is directed to an electronic device userinterface. Suitable electronic device user interfaces can comprise: ahousing having side walls defining an open upper end and a lowersurface; a biometric sensor capable of sensing a target biometricparameter having a sensor interface with a sensing side wherein thesensor interface is capable of positioning within the open upper end ofthe housing; a protective coating on the sensing side of the sensorinterface; and an integrated circuit, external to the housing, incommunication with the biometric sensor. In some aspects, the protectivecoating extends over or through one or more side walls of the housing.

Additionally, the biometric sensor further can comprise a flexiblecircuit substrate and at least one conductive trace connecting thebiometric sensor to the integrated circuit. The conductive traces of theflexible circuit substrate can also be positionable on at least one of aside of the flexible circuit substrate facing towards an exterior of thehousing and a side of the flexible circuit substrate facing towards aninterior of the housing. In some configurations, the device can furthercomprise one or more of each of: a potting material positionable betweenthe lower surface of the housing and the protective coating; a bezelextending from the side walls of the housing above the bottom of theprotective covering; and a removable bottom plate that can attach to thehousing to support the biometric sensor. In some configurations, theflexible circuit can wrap around the removable bottom plate.Additionally, an adhesive potting material can be provided between thebottom plate and the protective coating. In still other aspects, thebiometric sensor can be capable of capturing a fingerprint from a fingerof a user.

Additional aspects of the disclosure are directed to a method offabricating an electronic device user interface. The method cancomprise: providing a biometric sensor having a sensor interface with asensing side and one or more conductive traces thereon in communicationwith a flexible circuit; placing a protective coating on the sensingside of the biometric sensor; inserting the biometric sensor into ahousing; and providing an integrated circuit external to the housing incommunication with the biometric sensor. An additional step can include:forming the protective coating over one or more side walls of thehousing. The biometric sensor can be comprised of a flexible circuithaving a flexible substrate, wherein the method further comprises thestep of: forming at least one conductive trace connecting the biometricsensor to the integrated circuit.

Yet another step can include forming the one or more conductive tracesof the flexible circuit on at least one of a side of the flexiblesubstrate adjacent a finger of a user and a side of the flexiblesubstrate facing away from the finger. Still other steps can include oneor more of each of: providing an adhesive between the bottom portion ofthe housing and the protective coating; forming a bezel over at leastthe edges of the protective covering; providing a bottom plate thatattaches to the housing to enclose the biometric sensor; forming theflexible circuit around the bottom plate; and providing an adhesivebetween the bottom plate and the protective coating.

Still another aspect of the disclosure is directed to a method of usingan electronic device user interface. The method can comprise: providinga housing having side walls defining an open upper end and a lowersurface, a biometric sensor capable of sensing a target biometricparameter having a sensor interface with a sensing side wherein thesensor interface is capable of positioning within the open upper end ofthe housing, a protective coating on the sensing side of the sensorinterface, and an integrated circuit, external to the housing, incommunication with the biometric sensor; and capturing a fingerprintfrom a finger of a user when the finger is applied to the biometricsensor.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the disclosed subject matter are set forth withparticularity in the appended claims. A better understanding of thefeatures and advantages of the present invention will be obtained byreference to the following detailed description that sets forthillustrative embodiments, in which principles of the disclosed subjectmatter are utilized, and from which they can be illustrated and used,wherein in the accompanying drawings of which:

FIG. 1 shows partly schematically an internal portion of a twodimensional (“2D”) fingerprint sensor array package/housing according toaspects of embodiments of the disclosed subject matter;

FIG. 2 shows partly schematically a cross-sectional view generally alongthe line 2-2 in FIG. 1;

FIG. 3 shows a more detailed version of a portion of the cross-sectionalview of FIG. 2;

FIG. 4 shows top plan view of a sensor encapsulation assembly accordingto aspects of embodiments of the disclosed subject matter;

FIG. 5 shows a cross-sectional view of a sensor button switch assemblyfor a mobile communication device, according to aspects of embodimentsof the disclosed subject matter;

FIG. 6 shows a perspective view of a version of the sensor encapsulationassembly, according to aspects of embodiments of the disclosed subjectmatter;

FIG. 7 shows a more detailed view of a portion of FIG. 6;

FIG. 8 shows a cross sectional view of an example of a transition from asensor laminated package to a molded encapsulation, according to aspectsof embodiments of the disclosed subject matter;

FIG. 9 shows a cross-sectional view of a portion of FIG. 5;

FIGS. 10A-C show a cross-sectional view of an embodiment of a buttonhaving a fingerprint sensor incorporated therein;

FIGS. 11A-C show a cross-sectional view of another embodiment of abutton having a fingerprint sensor incorporated therein;

FIG. 12 is a perspective view of a housing with a fingerprint sensorpositioned therein;

FIGS. 13A-B illustrate fingerprint sensors suitable for use with thebutton interfaces disclosed herein; and

FIG. 14 is an illustration of a button having a fingerprint sensorincorporated therein.

DETAILED DESCRIPTION

According to aspects of embodiments of the disclosed subject matter asensor support housing/package 10, as illustrated schematically in FIG.1, is disclosed. The sensor 10 may be a biometric sensor, e.g., afingerprint sensor having a plurality of pixel locations formed ineither a linear one dimensional (“1D”) array or a two dimensional grid(“2D”) array, such as is shown schematically in FIG. 1. As shown by wayof example in FIG. 1, the 2D sensor array 10 may form a grid 20, havingtransmit/drive signal vertical traces 30 and generally perpendicularhorizontal receiver signal traces 32. The sensor 10 can also be seen toinclude a transmit/drive signal via section 40 to the top of theschematic illustration in FIG. 1, including transmit/drive signal vias44 and a receiver signal via section 42 to the left side of theillustration in FIG. 1, including receiver/response signal vias 46. Itwill be understood by those skilled in the art that the schematic viewof FIG. 1 is not to scale and also does not show all of the verticaltraces 30 or horizontal traces 32. It will be understood that usuallyeach of the vias 44 is electrically connected to a vertical trace 30 andeach of the vias 46 is connected to a horizontal trace 32, so that thereare in reality many more traces 30, 32 than illustrated in FIG. 1.

Assuming that the horizontal traces 32 are in the direction of the widthof the finger being sensed, the grid 20 would normally be about 12 mm inthat direction and would have around 200 traces 32. Ordinarily, for aplacement type 2D sensor array 10, the perpendicular vertical traces 30,aligned in the direction of the length of the finger, would be of thesame pitch, but would be more in number, e.g., 600, though schematicallyin FIG. 1 the grid 20 is shown to be square. It will also be understoodthat the grid 20 could be of 200 horizontal traces 32 across the widthof the finger and the vertical traces could be less than 200, e.g., asufficient number to make the grid 20 a 12 mm×4 mm grid array, by way ofexample, such as for a swipe sensor where the sensor captures so calledframes of, e.g., from 66 horizontal traces, forming scanned frames thatcan be reconstructed to form the entire fingerprint image, as is wellunderstood in the art. It will also be understood that the disclosedsubject matter could support the packaging of a linear one dimensionalcapacitive gap array, where there are many vertical traces 30 but onlyone horizontal trace 32, usually but not exclusively co-planer with thevertical traces 30, and acting as a transmitter plate to the manyperpendicular receiver plates 30 or a receiver plate to the manyperpendicular transmitter plates 30 facing the single plate across agap, e.g., forming a one dimensional linear capacitive gap array. Itwill also be understood that, as elsewhere discussed in the presentapplication there is generally at least one layer between the horizontaltraces 32 and the vertical traces 30, in a 2D grid array, which layer(s)is not shown in FIG. 1.

Turning now to FIGS. 2 and 3, there is shown partly schematically afirst cross-sectional view and an enlargement of that view, generallyalong the line 2-2 in FIG. 1. FIG. 2 shows in cross-section view asensor support housing/package 100, having a core layer 102, having athickness of about 100 μ, ±20 μ, an upper micro-printed circuit board(“PCB”) laminate layer 104, having a thickness of about 75 μ, ±10 μ anda lower micro-PCB laminate layer 106, having a thickness of about 75 μ,±10 μ on either side of the core layer 102. A transparent protectiveglass layer 120, having a thickness of about 10 μ, ±5 μ and an opaqueink rigid protective layer 122, having a thickness of about 15 μ, ±5 μalong with an upper solder mask layer 130, having a thickness of about25 μ, ±8 μ are arranged above the upper micro-PCB laminate layer 104. Alower solder mask layer 132, having a thickness of about 25 μ, ±8 μ liesbelow the lower micro-PCB laminate layer 106. These layers form acomposite laminate forming a pin grid array (“PGA”) package 100, towhich an integrated circuit die 140, having a thickness of about 150 μ,±12 μ may be attached using an under fill layer 150, having a thicknessof about 70 μ, ±10 μ.

Upper micro-PCB laminate top traces 170, may be formed partly in theupper micro-PCB laminate layer 104 and partly in the upper solder masklayer 130. Upper micro-PCB laminate layer bottom traces 172, may beformed, partly in the upper micro-PCB laminate layer 104 and partly inthe core layer 102. Lower micro-PCB laminate layer top traces 174, maybe formed partly in the lower micro-PCB laminate layer 106 and partly inthe core layer 102. Lower micro-PCB laminate bottom traces 176, may beformed partly in the lower micro-PCB laminate layer 106 and partly inthe lower solder mask layer 132.

Die connective pads 190 may be formed on the back side of the integratedcircuit die 140, and have attached to each of them a die connective stud192, as can be seen in more detail, e.g., in FIG. 3, which may be formedon the die 140, e.g., through openings in a mask layer on the back sideof the die 140, which may later be removed. The studs 192 may then besurrounded in the under fill layer 150 and serve to electrically connecta respective die connective pad 190 to a respective die connective stud192, which in turn connects through an opening 134 in the lower soldermask layer 132 to a respective lower micro-PCB laminate layer bottomtrace 176, e.g., through a bump 194 that may be grown on the respectivestud 192 and formed, e.g., of solder.

Core layer 102 vias 180, e.g., connecting a respective upper micro-PCBlaminate bottom trace 172 to a respective lower micro-PCB laminate toptrace 174 may be formed through the core layer 102, e.g., by laserdrilling. Upper micro-PCB laminate layer vias 182, e.g., connecting anupper micro-PCB laminate layer top trace 170 to a respective uppermicro-PCB laminate bottom trace 172, may similarly be formed through theupper micro-PCB laminate layer 104. Lower micro-PCB laminate layer vias184, e.g., connecting a lower micro-PCB laminate top trace 174 to arespective lower micro-PCB laminate layer bottom trace 176, maysimilarly be formed through the lower micro-PCB layer 106.

The die contact plates 190, grown on the wafer substrate forming the die140, may be made of any suitable conductive material, such as aluminum(“Al”), copper (“Cu”) or gold (“Au”), while the contact studs 192 mayalso be made from a suitable conductive material, e.g., Cu. The contactbumps 194 may be made, e.g., of solder and grown on the top of thecontact posts 192, after they are formed or while the masking materialstill covers the back side of the die 140 and may extend throughopenings 178 formed in the lower solder mask layer 132.

Ball grid array (“BGA”) solder balls 200 may extend through openings 178in the lower solder mask layer 132 and make electrical contact withlower micro-PCB laminate layer bottom traces 176, e.g., to connect thepackage 100 to other electrical components of the sensor/imager 10,e.g., through traces on a flexible or rigid substrate, e.g., 210, asshown in FIGS. 5 and 9, on which the package/housing 100 is mounted.

Turning now to FIG. 5 there is shown, by way of example, a sensorencapsulation assembly 202. A flex substrate 210, as illustrated in FIG.5, can be made from a suitable flexible and dielectric material, such asa polyimide film, like Kapton®. The top plan view of FIG. 4 showsencapsulation material 220 encapsulating the package/housing 100, as isshown in more detail in cross section in FIGS. 5 and 9, with theencapsulation material 220, such as Mold Compound or any number of wellknown molding compounds, surrounding the package/housing 100, andfilling in around the BGA solder balls 200, which may, e.g., makeelectrical contact to a trace(s) 208 on the flex material 210.

Turning now to FIG. 5, there in shown in cross section an example of anembodiment of a mobile device biometric sensor and switch combination300. The mobile device biometric sensor and switch combination 300 fitswithin an opening 304 in a mobile device housing 302, such that theupper sensor surface 222, formed by the encapsulation material 220 ofthe housing is generally flush with the outer surface of the mobiledevice housing 302. The encapsulated sensor package/housing 100 may bemounted on a flexible substrate 210, as shown in FIG. 9 that may beattached to a mobile device waterproof rubber seal member 310, e.g.,with a waterproof tape 320. The sensor device package/housing may beentirely encased in the encasing material as illustrated in FIG. 9, or,as shown in FIGS. 5 and 7 the transparent glass layer 120 and overlyinghard opaque coating layer 122 may be exposed through an opening 230 inthe encapsulating material 220 to facilitate fingerprint sensing. Amolded frame/spacer 240, which may be made of the same material as theencapsulating material 220, or, as shown in FIGS. 6-8, may be molded inthe encapsulation process. The spacer/frame 240 may have a flange 280,and may serve to hold the encapsulated package/housing 100 on theopening 302. FIG. 8 shows a cross-sectional view of a portion of anexemplary package/housing 100 within, e.g., a sensor encapsulationassembly, surrounded by encapsulation material 220 and covered by arelatively thin layer of rigid material 222, applied as an inkoriginally and allowed to cure.

The mounting of the package/housing 100 to the flex strip 210 may givethe entire assembly enough flexibility such that, when a finger or otherobject is pressed against the top of the housing, package 100 can moveenough to operate an underlying mechanical switch, such as a dome switch330, which may include a depression member 323 and a deformable contact332. The switch 330 may be connected to circuitry (not shown) on acircuit board 350 within the body of the mobile device. A toggling twoposition element 332 may form the other contact of the switch 330, suchthat when the depression member 323 is moved into the two positionelement it “clicks” to a non-contacting dome position and the switch 330is open when the pressure on the package/housing is removed. When thedepressing element is moved back into contact with the two positionelement 332, it is “clicked” back to the contacting position and theswitch 330 remains closed when the pressure is removed from thepackage/housing 100. A pair of stops 352 engaging the circuit board 350can ensure the flex material does not bend too severely, thus damagingthe relatively rigid package/housing 100. An interposer plate 360,attached to the bottom of the flexible strip 210, can serve to move thedepression member 323, when downward pressure is put on thehousing/package 100.

The spacer 240 may be formed with a rounded edge 250, to protect thefinger of the user. As shown in more detail, in FIGS. 6-8, instead of aseparate spacer 240, the encapsulation material may be initially moldedaround the package/housing 100 to form, e.g., a slanted side wall 252,rounded corners 260 the rounded top circumference 250 of the moldedencapsulation, and the flange 280. In a variation of the process of FIG.4, the molded encapsulation material 220 may be formed over a packagehousing 100 attacked to traces on the flexible material substrate 210formed to have a trace extension 284, which may serve to electricallyconnect the sensor 10 and IC 140 to other components of the system.

It will be understood by those skilled in the art that according toaspects of embodiments of the disclosed subject matter, the disclosedmulti-layer laminate substrate technology has been employed to create afinger print sensor with a very durable package/housing construction,for biometrically authenticating a user of the mobile device and alsosuitable for use as part of a mobile device mechanical switch, e.g., forturning the mobile device on and off. The sensor may be formed of a 1Dor 2D grid array of various shapes and sizes, with one dimensiontypically at least as wide as normal human finger. The grid can beformed, as an example, by traces forming conducting leads on opposingsides of a top layer in a laminate of layers on opposing sides of arelatively rigid and strong, e.g., reinforced core layer. Electricaldrive circuitry may be connected to the traces on one side of thelaminate layer and pick-up/response circuitry may be connected to thetraces on the opposing side of the upper laminate layer, with thetransmit drive traces typically formed closer to the sensing surface ofthe sensor, i.e., the top surface of the upper laminate layer.

This top surface (top meaning surface closest to the finger duringfinger print acquisition), as noted, is usually configured as thetransmitter traces and the other metal traces on the reverse side of thelayer (farther away from the finger), layer is usually configured as thereceiver. response signal traces. As is well known in the art, thetraces formed in a 1D or 2D array constitute pixel locations where thepresence of the finger creates variations in the receive signal responseto the transmitted signal, mostly due to variations in the capacitivecoupling of the two through the finger near the top of the sensor 10 dueto capacitive differences between the presence of a fingerprint valleyor ridge in the vicinity of the given pixel location. These variationsare detected to generate an finger print image either partly or whollywithin the integrated circuit, which can also create the drive signalsand time their application to drive signal traces in the grid 10.

It will also be understood that the height of the package/housing canvary based on the BGA size, e.g., in order to conform to differingheight requirements. Package/housing size can, e.g., correspond tosensing linear array or grid array area, e.g., about 122 mm across inthe direction of the width of the finger and the same or more in thedirection of the length of the finger. The package body can, e.g., besquare, e.g., in embodiments designed for housing the sensor on the topof or embedded within the housing as required to create a round button.The package may have some or all sides formed with a bevel cut packageedge, e.g., down to about a 100 μ depth, which may, e.g., be formed in atwo pass singulation of individual packages/housings from a plurality ofpackages/housings formed in one operation as discussed elsewhere in thepresent application.

A PCB or flex interposer may be required to make a housing in which thepackage/housing is part of actuating a mechanical switch button. Buttonsmay be manufactured, e.g., by placing a flex strip(s) in a molding jig.The button housing may, e.g., be molded around the biometric sensorformed within the multilayer flip chip housing/package, e.g., with moldcompound surrounding the flip chip placed on the flex strip, e.g., in arow of chips format. The flex strip may form a substrate having, e.g., athickness of around 80 μ-120 μ. The top portion of the mold material mayhave, e.g., a thickness of around 50 μ and a bottom mold thickness ofaround 1 mm.

According to aspects of embodiments of the disclosed subject matter, asingle sided molded package/housing may be created, e.g., having a basesubstrate, which may be flexible, or rigid, e.g., a PCB ormicro-laminated layer PCB, as discussed elsewhere in the presentapplication, by way of illustration, by the mounting of a flip chiplaminate package, described in the present application, to thesubstrate. The assembly, substrate plus flip chip laminate package, canthen be place entirely of mostly within an encapsulation material thatmay then be molded into a desired size and shape, e.g., by the use ofmoldable encapsulation material, such as well known molding compounds,plastics, resins, etc. The molding material may be used to fill underthe flip chip package and/or around the perimeter and/or on the surfaceof the package to form a molded button. Such a molded button may beutilized solely with the biometric sensor element to sense fingerpresence and/or surface movement, and, in response, act as a button, ormay be combined with an interposer, such as made from a rigid material,like a PCB, or flexible, such as a flex substrate, e.g., to interactwith an adjacent mechanical switch when the biometric, i.e., the fingerpresses down on the sensor area and thus on the entire package/housing.

The substrate/interposer with a flip chip package attached, andencapsulated by use of injection/transfer/compression molding, or thelike, may include on the sensing side an encapsulation thickness that isrelatively thin, or even non-existent and selected and adjusted toestablish a desired sensing distance from the surface of the actualsensing traces in the flip chip package. Sensing distance can beimportant to accurate data capture. As one option according to aspectsof embodiments of the disclosed subject matter, the sensing side of thepackage can be encapsulated to protect the sensing area from surface,impact, or moisture damage. This can be done, by way of example, in asingle molding step, by using materials with filler sizes appropriatefor a top minimum thickness. In an example the minimum thickness overthe flip chip package can be, e.g., 30-50 μ. This thin layer of materialwould require the use of a fine filler, e.g. one with filler sizes of 15μ or smaller in the molding compound.

In another example, the assembly can also be encapsulated on all sideswith the exception of the upper sensor surface. In such a case, e.g.,where the sensor surface is not encapsulated, it can be protected byapplying protective coating, e.g., as noted elsewhere, a spray inkcoating that hardens as it is cured, and/or a glass or other transparentplastic coating, of, e.g., by a second molding step. The protectivecoating/coatings to the surface of an exposed flip chip laminatesubstrate and/or encapsulating area is contemplated.

In a third option another variant may be to add a protectivecoating/coatings to the surface of the flip chip package prior toassembly on the button substrate and further encapsulation. Such anencapsulation molding process can allow for a wide variety ofcustomization of button sizes and shapes with a single flip chippackage/housing by changing of the mold size and shape. Suchencapsulation molding processing and materials can also allow radiuscorners and edges that cannot be as easily achieved with standardlaminate package technologies.

According to aspects of embodiments of the disclosed subject matter alow cost customizable finger print sensor button, e.g., for the mobilecommunication device market can be produced. The package/housing bodymay be, e.g., 10.5 mm×4.0 mm. The package housing may be mounted on aflexible substrate and with supporting components elsewhere on thesubstrate or on a rigid PCB or a mobile phone board. It is also possiblefor the flip chip package housing to be mounted to a motherboard withthe specified other components also so mounted.

It will be understood by those skilled in the art that there isdisclosed in the present application a biometric sensor that maycomprise a plurality of a first type of signal traces formed on a firstsurface of a first layer of a multi-layer laminate package; at least onetrace of a second type, formed on a second surface of the first layer oron a first surface of a second layer of the multi-layer laminatepackage; and connection vias in at least the first layer electricallyconnecting the signal traces of the first type or the signal traces ofthe second type to respective circuitry of the respective first orsecond type contained in an integrated circuit physically andelectrically connected to one of the first layer, the second layer or athird layer of the multi-layer laminate package. The first type ofsignal trace may comprise drive signal traces and the second type oftraces may comprise at least one receive signal trace or the first typeof traces comprising receive signal traces and the second type of tracescomprising at least one drive signal trace. The at least one trace ofthe second type may comprise one trace of the second type and the sensormay comprise a one dimensional linear array capacitive gap biometricsensor. The at least one trace of the second type may comprise aplurality of traces of the second type and the sensor may comprise a twodimensional array capacitive biometric sensor.

The first layer may comprise a circuit board layer and the second layermay comprise a core layer attached to one side of the circuit boardlayer. A third layer comprising a circuit board layer may be attached toanother side of the core layer. The biometric sensor may be encapsulatedon all sides except for a top finger sensing side and may be attached toa substrate. The biometric sensor may be encapsulated on all sides. Thebiometric sensor may be encapsulated by moldable plastic material formedaround the package by a molding process, which also may form anencapsulation molded with rounded edges and corners. The biometricsensor may comprise a biometric sensor mounted on a portable electronicdevice, and may also cooperate mechanically with elements of a switchwithin the portable computing device to operate the switch.

Turning now to FIG. 10A is a cross-sectional view of an embodiment of abutton 1100 having a one dimensional (1D) or two dimensional (2D)biometric sensor 1130, such as a chip on flex (COF) fingerprint sensor1130, incorporated therein. The button 1100 can have an upper surface1102 and a lower surface 1104 and may be configurable to provide, forexample, a glass or suitable hard coat or film top layer 1110 having anupper surface 1112 and a lower surface 1114, which can be surrounded bya housing 1120 on two or more sides. In this configuration, the edges ofthe top layer 1110 can be enclosed by a bezel 1122, such as a rim thatretains the top layer 1110 within the housing 1120. The upper surface1112, of the top layer 1110 can serve as an interface for a fingerduring use of the device and capture of biometric information from theuser's finger. The top layer 1110 can be configured to provideprotection for the biometric sensor 1130. The top layer 1110 can becomposed of different materials and/or colors which may also providedecorative identification. Additionally, the top layer 1110 can beformed from a hard material providing mechanical protection to thesensor tracer elements formed, e.g., on the flexible circuit substrate1130. The bottom portion of the housing 1120 can also provide mechanicalsupport for the button assembly 1100.

The housing 1120 can be formed from, for example, polycarbonate (PC),acrylonitrile-butadiene-styrene (ABS) or other suitable material,including any thermoplastic characterized by high-impact strength, aswell as metals such as aluminum and titanium. The housing 1120 can beconfigured to have a base 1124, and parallel side walls 1126 (in twodimensional cross-section), an aperture 1128 can be provided throughwhich flexible circuit substrate 1132 of the sensor 1130 passes toconnect to the integrated circuit 1134 which can be positioned away fromthe housing 1120.

The top layer 1110 can be formed from glass or any other suitablematerial such as shatter resistant substitutes for glass, includingpolymethylmethacrylate (PMMA), polyethylene terephthalate (PET), etc.The biometric sensor element substrate 1130 can be formed from, forexample, from a flexible circuit substrate formed with flex circuitmetal tracer elements on top of a flexible film substrate 1132 with themetal traces being in electrical communication with an integratedcircuit chip 1134. The integrated circuit chip 1134 need not form partof the stack of materials, and thus, in that configuration, can provideno mechanical functionality to the sensor/finger interface or mechanicaloperation of the button 1100. An adhesive or potting material 1140 inthe aperture, such as thermo-setting plastic or silicone rubber gel, canbe provided that secures and/or stabilizes the positioning of the sensorflexible circuit substrate 1130, forming the sensor 1130 in a positionbetween a bottom portion 1124 of the housing 1120 and the top layer 1110which is engaged by the user during use. The adhesive or pottingmaterial 1140 can consist of different regions or layers depending onthe assembly method.

Additionally, the adhesive or potting material 1140 may also consist ofmultiple adhesives or potting materials depending on assembly method andrequired properties of the button 1100. Dimensions of the form factorcould be less than or equal to 900 mm², less than or equal to 400 mm²,less than or equal to 225 mm², less than or equal to 100 mm², in a firsttwo dimensional aspect. In some embodiments the thickness of the formfactor is less than or equal to 2 mm or more preferably less than orequal to 1.5 mm. Further embodiments can have the form factor thicknessless than or equal to 1 mm.

The potting material 1140 in the opening can be selected such that itprovides mechanical support for the sensor 1130. Impact resistance ofthe button 1100 can be enhanced by maintaining a high hardness (modulus)throughout and/or thin adhesive thickness. Further the siliconintegrated circuit (IC) chip 1134 may not be included in this pottingarea to avoid thermal expansion, humidity expansion and generaldurability issues that might arise. That is to say, the flexiblesubstrate 1138 can be unfolded from under the button 1100, asillustrated, e.g., in FIG. 14.

As will be appreciated by those skilled in the art, biometric sensorscan include, for example, a fingerprint sensor, a velocity sensor, andan integrated circuit which is electrically connected to the fingerprintsensor and the velocity sensor. Biometric sensors can further includesensors adapted and configured to capture one or more parameters of, forexample, a fingerprint. Conductive traces (not shown in FIG. 10A) of animage sensor and velocity sensor can be etched or otherwise formed on aside of the flexible circuit substrate 1130 facing the upper surface1112 of the button 1100. Moreover, the traces can be positioned on theflexible substrate 1130 such that the traces are up (and thus on anupper surface 1136 of the substrate 1132 proximal to the top layer1110), or the traces are down (and thus on a lower surface 1138 of thesubstrate distal the top layer 1110). In some configurations, the flexcircuit 1130 on the flex substrate 1132 can be configurable to havefunctionality (i.e., traces formed) on both the upper surface 1336 andthe lower surface 1138 which enables the width of the flex 1130 to bereduced, and also reduces the overall package size. Moreover the button1100 can be part of a mechanically functional switch or a mechanicallyfixed button. Additionally, the button 1100 can be used for biometricsensing (fingerprint sensing), navigation, or touch sensing.

As will be appreciated in reviewing FIG. 10A, the IC chip 1134 need notbe positioned within the stack of materials. Where the IC chip 1134 ispositioned away from the stack of materials forming the button, thebutton 1100 can achieve a more compact profile and lower height whichmakes the button 1100 more adaptable to be incorporated into anelectronic device, such as a smart phone or touch pad. Additionally, theconfiguration enables the properties (e.g., cover, adhesive material,housing) to be tuned for functionality and durability.

In configurations where the conductive traces are positioned on the topside of the flex 1136, a protective coating can be applied to the uppersurface 1136 of the flex substrate 1132 itself, over the image sensorand velocity sensor to provide electrical isolation and mechanicalprotection of the sensors. Alternatively, conductive traces of an imagesensor can be formed on a bottom-side 1138 of a substrate 1132, whereinthe substrate 1132 of the flex circuit 1130 acts as a protective coatingand can be further improved with a hard coating applied to the uppersurface 1136 of the flex circuit 1130 itself.

Further details about fingerprint sensor configurations are containedin, for example, U.S. Pat. No. 7,751,601 to Benkley III for FINGERPRINTSENSING ASSEMBLIES AND METHODS OF MAKING; U.S. Pat. No. 7,099,496 toBenkley III for SWIPED APERTURE CAPACITIVE FINGERPRINT SENSING SYSTEMSAND METHODS; U.S. Pat. No. 7,463,756 to Benkley III for FINGER POSITIONSENSING METHODS AND APPARATUS; U.S. Pat. No. 7,460,697 to Erhart et al.for ELECTRONIC FINGERPRINT SENSOR WITH DIFFERENTIAL NOISE CANCELLATION;U.S. Pat. No. 7,146,024 to Benkley III for SWIPED APERTURE CAPACITIVEFINGERPRINT SENSING SYSTEMS AND METHODS; U.S. Pat. No. 6,400,836 toSenior for COMBINED FINGERPRINT ACQUISITION AND CONTROL DEVICE; and U.S.Pat. No. 6,941,001 to Bolle for COMBINED FINGERPRINT ACQUISITION ANDCONTROL DEVICE. As will be appreciated by those skilled in the art, thesensor can be a 1D swipe sensor, a 2D touch sensor, a 2D motion sensor,a 2D sensor having two layers of electrodes, a 2D sensor having a singlelayer of electrodes, a 2D sensor with electrodes on either side of theflex substrate 1130 substrate. Moreover, multiple conductor materialscan be used to form the sensor, such that different layers are made fromdifferent materials to achieve different results and for differentreasons.

The button 1100 can be configurable such that it has a transparentinterface, an opaque top coat, or a mask layer, and can be formed suchthat the upper surface material is not visually transparent.Additionally, the upper surface can be configurable such that itprovides a variety of tactile interfaces, e.g., rough or smooth. An“anti-fingerprint and/or anti-smudge” (“AF”) and/or a hard coating canbe applied.

FIG. 10B is a cross-sectional view of another configuration of a button1100′ having a 1D or 2D biometric sensor, such as a COF fingerprintsensor, incorporated therein. In this embodiment the top layer 1110′,formed from glass or any other suitable material such as shatterresistant substitutes for glass, including polymethylmethacrylate(PMMA), polyethylene terephthalate (PET), extends at least partly on topof some or all of the sides 1126′ of the housing 1120′.

FIG. 10C is a cross-sectional view of another configuration of a button1100″ having a 1D or 2D biometric sensor, such as a COF fingerprintsensor, incorporated therein. In this embodiment the top layer 1110″ isover-molded which extends the top layer 1110″ over and at least partlysurrounds at least one side 1126″ of the housing 1120′. This top layer1110″ may be formed by over-molding, wet coating or any suitable method.

FIG. 11A is a cross-sectional view of another configuration of a button2100 having a biometric sensor 2130 incorporated therein. The button2100 is configurable to provide, for example, a glass or suitable hardcoat or film top layer 2110 which is surrounded by a housing 2120. Thehousing 2120 can be formed from polycarbonate (PC) or other suitablematerial including but not limited to metals such as aluminum. Thebiometric sensor 2130 can be comprised, for example, from a flexiblecircuit substrate 2132 which is in electrical communication with anintegrated circuit 2134. This configuration is illustrated to have anadhesive or potting material, 2140 which may or may not be necessarydepending on the method of manufacture. The flexible circuit 2132 issecured and/or stabilized about an insert plate or support 2160 that canbe fitted within the housing 2120 and, for example, clipped into place.In this configuration the flexible circuit 2132 wraps around the insertor plate 2160 and then the flex/plate combination can be clipped intothe housing 2120. In another example the insert or plate can be clippedinto the housing 2120 and then the flex substrate 2132 can be wrappedaround the plate 2160. Additionally, the plate 2160 may be placed intoposition within the housing 2120 using an adhesive, e.g., filling theopening 2140, where the flex circuit 2130 fits instead of being clippedinto place. Adhesive and/or potting materials may also be optionallyused. In some configurations, the glass, hard coat or hard film can bebonded directly to the sensor flexible circuit 2130 flexible substrate2132 or can be so bonded with an adhesive.

FIG. 11B is a cross-sectional view of another embodiment of a button2100′ having a fingerprint sensor 2130′ incorporated therein. The button2100′, containing a flexible substrate 2132′ with the sensor elements2130′ wrapped around an insert or plate 2160′ in electricalcommunication with the sensor IC 2134′ is configurable to provide, forexample, a top layer 2110′ that extends at least partly on top of someor all of the sides 2126′ of the housing 2120′.

FIG. 11C is a cross-sectional view of another embodiment of a button2100′ having a fingerprint sensor 2130″ incorporated therein. The button2100″, containing a flexible substrate 2132″ with the sensor elements2130″ wrapped around an insert or plate 2160″ in electricalcommunication with the sensor IC 2134″ can be configurable to provide,for example, a top layer 2110″ that extends over and at least partlysurrounds at least one side of the housing, as shown, e.g., at 2112″ oneither side of the side walls 2126″. This top layer 2110″ may be formedby over-molding, wet coating or any suitable method.

FIG. 12 is a perspective view of a button 3100 having a housing 3120with a fingerprint sensor 3130 therein.

FIGS. 13A-B illustrate fingerprint sensors 130 suitable for use with thebutton interfaces disclosed herein. Suitable 1D sensors possess from 90to 300 pixels, or more preferably from 114 to 200 pixels. Suitable 2Dsensors possess arrays of pixels in the range of 90 to 300 pixels by 90to 300 pixels, or more preferentially a range of 114 to 200 pixels by114 to 200 pixels. A size is from 8 to 30 mm across the broadest length,or more preferably from 6 to 20 mm. FIG. 13A illustrates an example of a2D touch sensor layout 4130 on flex; FIG. 13B illustrates an example ofa 1D sensor layout 4130′ on flex.

FIG. 14 is an illustration that shows a top view of a button 5100 havinga fingerprint sensor incorporated therein. The button 5100 has apill-shape profile as illustrated, but could be square or circular asrequired from the implementation. The biometric sensor elements 5130,either 1D or 2D, can be positioned within a portion of the housing 5120and positioned to be attached to the top layer 5110 (same profile ashousing 5120). The flexible substrate 5132 can extend from the embeddedsensor such that the substrate 5132 can be wrapped around, for example,a plate (not shown), or otherwise configured to fit within the housing5120. The integrated circuit 5134 which controls the operation of thesensor/button 5100 is on an opposing end of the flexible substrate 5132and in electrical communication with the sensor elements in thesensor/button 5100.

II. Methods of Use

The button interfaces may be housed in a host electronic device andconfigured to perform both object image capture and at least one of anactivation of the host device, an activation of a host device functionand an input to the host device. The button interfaces may furthercomprise the button interfaces configured to allow a user to contact theswitch simultaneously with providing object image data through anintersection of the at least one drive line and the at least one pickupline. The object may a finger and the button interfaces configured tosense a fingerprint image. The button interfaces described above canalso be used to create a functional button (e.g., on/off), to providenavigation functionality, and/or to provide biometric sensing (such asfingerprint sensing).

III. Methods of Manufacture

In one manufacturing example, the button is manufactured according tothe following:

-   -   Singulate flex by, for example, laser cutting adjoining        laminated material.    -   ACF attach connection to flex may occur prior to singulating        flex, after singulating flex or after final button assembly.    -   Form housing, for example, using a cast or machine.    -   Provide flex sensor with the ACF board.    -   Flex bonded to housing.    -   Assemble housing if needed.    -   Form top layer either on the flex area only or on the housing        only or both the flex and housing. The top layer could be a        curable wet coat or cast or hard film bonded with adhesive among        other materials.    -   ACF attach connection to flex if not connected previously.

In another manufacturing example, the button is manufactured accordingto the following:

-   -   Singulate flex.    -   ACF attach connection to flex may occur prior to singulating        flex, after singulating flex or after final button assembly.    -   Form top layer on the flex area. The top layer could be a        curable wet coat or cast or hard film bonded with adhesive among        other materials. Applying top layer may occur prior to        singulating flex.    -   Flex bonded to housing.    -   Housing assembled if needed.    -   ACF attach connection to flex if not connected previously.

In still another manufacturing example, the button is manufacturedaccording to the following:

-   -   Singulate flex.    -   ACF attach connection to flex may occur prior to singulating        flex, after singulating flex or after final button assembly.    -   Top layer bonded to housing. The top layer could be a curable        wet coat or cast or hard film bonded with adhesive among other        materials.    -   Bond flex to top layer and/or housing.    -   Form support behind flex either by filling using an epoxy and/or        bond plate in place.    -   ACF attach connection to flex if not connected previously.

In a fourth manufacturing example, the button is manufactured accordingto the following:

-   -   Singulate flex.    -   ACF attach connection to flex may occur prior to singulating        flex, after singulating flex or after final button assembly.    -   Attach flex to the bottom plate of the housing.    -   Attach plate/flex combination to the housing.    -   Attach top layer to the housing.    -   Use adhesive or potting material if needed to fill volume.    -   ACF attach connection to flex if not connected previously.

The manufacturing process is configurable to simplify the buttonmanufacturing process using advanced manufacturing techniques whileoptimizing image capture through the molding compounds and/or layers.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A sensor assembly, comprising: a flexiblesubstrate; and an encapsulated sensor package mounted on the flexiblesubstrate; wherein the encapsulated sensor package includes a housingbonded to the flexible substrate; wherein the top of the housingcorresponds to an interface for a finger or other input object; whereinthe sensor assembly further comprises a switch, wherein the switch isconfigured to be depressed based on an input object being pressedagainst the top of the housing; and wherein the encapsulated sensorpackage comprises multiple layers and multiple types of signal traces.2. The sensor assembly according to claim 1, wherein the encapsulatedsensor package comprises: an upper circuit board layer; a core layer,disposed below the upper circuit board layer; and a lower circuit boardlayer, disposed below the core layer; wherein a first type of signaltraces is disposed on a first surface of the upper circuit board layer;wherein a second type of signal traces is disposed on a second surfaceof the upper circuit board layer or on a first surface of the corelayer.
 3. The sensor assembly according to claim 2, wherein theencapsulated sensor package further comprises: an integrated circuit,disposed below the lower circuit board layer, wherein the first type ofsignal traces and the second type of signal traces are electricallyconnected to the integrated circuit through connection vias.
 4. Thesensor assembly according to claim 2, wherein the first type of signaltraces corresponds to drive signal traces; and wherein the second typeof signal traces corresponds to receive signal traces.
 5. The sensorassembly according to claim 1, wherein the sensor assembly is disposedwithin an opening in a mobile device housing, and the top surface of thehousing of the encapsulated sensor package is flush with an outersurface of the mobile device housing.
 6. The sensor assembly accordingto claim 1, wherein the flexible substrate is configured to flex basedon the input object being pressed against the top of the housing, andwherein the sensor assembly further comprises one or more stopsconfigured to limit flexing of the flexible substrate.
 7. The sensorassembly according to claim 1, wherein the switch comprises: adepression member; and a toggling two position element; wherein thedepression member and the toggling two position element being in contactwith one another corresponds to a closed state of the switch, and thedepression member and the toggling two position element not being incontact with one another corresponds to an open state of the switch. 8.A sensor assembly, comprising: a flexible substrate; and an encapsulatedsensor package mounted on the flexible substrate; wherein theencapsulated sensor package comprises: an upper circuit board layer; acore layer, disposed below the upper circuit board layer; and a lowercircuit board layer, disposed below the core layer; wherein a firstplurality of traces is disposed on a first surface of the upper circuitboard layer; wherein a second plurality of traces is disposed on asecond surface of the upper circuit board layer or on a first surface ofthe core layer; wherein the encapsulated sensor package furthercomprises connection vias which traverse the core layer and areelectrically connected to the first plurality of traces in the uppercircuit board layer.
 9. The sensor assembly according to claim 8,wherein the encapsulated sensor package further comprises: an integratedcircuit, disposed below the lower circuit board layer, wherein the firstplurality of traces are electrically connected to the integrated circuitthrough the connection vias.
 10. The sensor assembly according to claim8, wherein the first plurality of traces comprise drive signal traces;and wherein the second plurality of traces comprise receive signaltraces.
 11. The sensor assembly according to claim 8, wherein the sensorassembly is disposed within an opening in a mobile device housing, andthe top surface of the encapsulated sensor package is flush with anouter surface of the mobile device housing.
 12. The sensor assemblyaccording to claim 8, wherein the sensor assembly further comprises aswitch, wherein the switch is configured to be depressed based on aninput object being pressed against the encapsulated sensor package. 13.The sensor assembly according to claim 12, wherein the flexiblesubstrate is configured to flex based on the input object being pressedagainst the top of the housing, and wherein the sensor assembly furthercomprises one or more stops configured to limit flexing of the flexiblesubstrate.
 14. The sensor assembly according to claim 12, wherein theswitch comprises: a depression member; and a toggling two positionelement; wherein the depression member and the toggling two positionelement being in contact with one another corresponds to a closed stateof the switch, and the depression member and the toggling two positionelement not being in contact with one another corresponds to an openstate of the switch.
 15. A sensor assembly, comprising: a flexiblesubstrate; and an encapsulated sensor package mounted on the flexiblesubstrate; wherein the encapsulated sensor package comprises: an uppercircuit board layer; a core layer, disposed below the upper circuitboard layer; and a lower circuit board layer, disposed below the corelayer; wherein a first plurality of traces is disposed on an uppersurface of the upper circuit board layer; wherein a second plurality oftraces is disposed on a lower surface of the upper circuit board layer;and wherein the encapsulated sensor package further comprises a firstplurality of connection vias which traverse the core layer and areelectrically connected to the first plurality of traces in the uppercircuit board layer and a second plurality of connection vias whichtraverse the core layer and are electrically connected to the secondplurality of traces in the upper circuit board layer.
 16. The sensorassembly according to claim 15, wherein the encapsulated sensor packagefurther comprises: an integrated circuit, disposed below the lowercircuit board layer, wherein the first plurality of traces and thesecond plurality of traces are electrically connected to the integratedcircuit through the first plurality of connection vias and the secondplurality of connection vias.
 17. The sensor assembly according to claim15, wherein the first plurality of traces comprise drive signal traces;and wherein the second plurality of traces comprise receive signaltraces.
 18. The sensor assembly according to claim 15, wherein thesensor assembly is disposed within an opening in a mobile devicehousing, and the top surface of the encapsulated sensor package is flushwith an outer surface of the mobile device housing.
 19. The sensorassembly according to claim 15, wherein the sensor assembly furthercomprises a switch, wherein the switch is configured to be depressedbased on an input object being pressed against the encapsulated sensorpackage.
 20. The sensor assembly according to 19, wherein the flexiblesubstrate is configured to flex based on the input object being pressedagainst the top of the housing, and wherein the sensor assembly furthercomprises one or more stops configured to limit flexing of the flexiblesubstrate.